divmod: recursive -> iterative

1 files changed, 1 insertions, 0 deletions

diff --git a/numalgo.cpp b/numalgo.cpp
index ee77afc..a8f2321 100644
--- a/numalgo.cpp
+++ b/numalgo.cpp
@@ -40,6 +40,7 @@ Bigint expmod(const Bigint &b,const Bigint &e,const Bigint &m){
 	assert(e>=0);
 	assert(m>=1);
 	if(m==1)return Bigint::zero;
+	if(e==0)return b;
 	Bigint res(1);
 	vector<bool> bits(e.bits());
 	for(int i=bits.size()-1;i>=0;i--){